This invention relates generally to automated railroad operation, and more particularly, to a method and apparatus for determining the alignment of a train inspection sensor.
Modern railroad car wheel bearings are permanently lubricated sealed units designed to last for the life of the car. However, during operation, excess friction between the axle and the bearing may produce excess heat, resulting in a condition referred to as a hot box. Moreover, when a bearing begins to operate above a predetermined temperature, continued movement of the car may cause the bearing to seize. As a result, the railroad service industry has devoted significant resources to building detectors that automatically check passing trains for hot boxes and/or hot wheels. Such detectors are generally spaced along railroad tracks at about twenty to fifty mile intervals along main-line track, and many are necessarily located in remote places.
At least one known detector includes a bearing temperature sensing unit for focusing infrared radiation that is transmitted from passing railcar bearings onto an infrared sensor. The bearing temperature sensing unit is coupled to electrical circuitry which develops a signal that is representative of the journal temperature. One bearing temperature sensing unit is placed along one rail of the tracks and a second bearing temperature sensing unit is placed along the other rail of a set of tracks, so that both sides of a train can be monitored. Electrical lines connect these trackside bearing temperature sensing units to processing circuitry which is generally located in a “bungalow” close to the tracks. The primary use of the detector is to detect overheated bearings and alert the train operator to prevent possible damage to the railcar bearings.
In operation, if the hot box detector detects a hot box condition, a signal that indicates that the temperature of a wheel journal exceeds a predetermined value is then transmitted. Specifically, when a hot box condition is detected, i.e. the signal triggers an alarm, the train car is stopped to manually inspect the suspect wheel bearing or hot box.
The effectiveness of the hot box detector system depends on various factors, including the alignment of the bearing temperature sensing units. For example, a misaligned bearing temperature sensing unit may sense the infrared energy from the brakes instead of the bearings. If this signal generated from the brakes exceeds the predetermined hot bearing alarm level, the hot box detector will falsely alarm, thereby causing an operator to stop the train and manually inspect the suspect wheel bearing or hot box. Such misalignment of the bearing temperature sensing unit may arise from several causes, such as, but not limited to, being struck by a passing train, being struck by a passing vehicle, being misaligned as a result of the weather, and/or through vandalism. As a result, misalignment of the bearing temperature sensing unit misalignment may lead to false alarms thus causing a false stop to occur.